KTM 790 takes a few tries to start

Discussion in 'Parallel World (790/890)' started by doctorblanco, Sep 10, 2019.

  1. Smashy

    Smashy Been here awhile

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    Maybe it has something to do with the gas you put it?
  2. Dan D.

    Dan D. Long timer

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    Got my bike back today after the 1v29 update...

    Bike still stalls and now I don't have my "free" quick shifter anymore either. Lol...
  3. Dan D.

    Dan D. Long timer

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    The favorites is nice.. guess I should have looked at that closer before. Can add all kinds of stuff in there.

    PXL_20210312_235352462.MP.jpg


    I don't recall the "extra functions" before... I assume that's where you're listed options are shown, such as rally and quick shifter?

    PXL_20210312_235112605.jpg


    Sorry for the dumb questions.. I'm sure I should RTFM.
  4. WI-790R

    WI-790R Been here awhile

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    More often than not, I tend to think things are over priced. Then there’s PCBs shipped from China to my door for way less than I’d have guessed possible. The components from Mouser were delayed, but are due to arrive Monday. I hope to populate a couple boards next week and confirm the circuit works as intended.

    I guess we still don’t know if more fuel at startup will keep it from stalling. If that does prove true, then the question becomes whether asking the ecu for more fuel for only 10-20s will fly under the radar, and not be calibrated out over time..........

    D0CF35C8-98A0-4CF7-BAD6-F61EA9F9DC77.jpeg
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  5. hcd

    hcd Been here awhile

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    Don't feel bad, I don't even know how to clear the trip meter, it reads the same as my odometer.
  6. Dan D.

    Dan D. Long timer

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    Lol, same here. :D

    I noticed the fuel pump "whine" seems to run twice now... Not sure if that's an update on v29.

    I joked earlier my bike still stalls, but it actually didn't... And seems to run better, but they claim it doesn't address the cold start issue. My stalling problem went away about 3 weeks ago, right after I switched to ethanol free gas. Not sure if that's related or not though.
  7. SoilSampleDave

    SoilSampleDave Dr. Zaius was right!

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    Well, there is more “energy” in any size droplet of real gas vs gas spiked with ethanol, so it’s not as crazy as it sounds. In fact, is ethanol laced gas even a thing in Europe? That might explain a thing or two.
  8. bikemoto

    bikemoto Tyre critic

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    Or not put in it.

    I was going to write that the tank is nearly empty, showing 30 km to go. But it's been like that for a few days with the starting problem present. I've only done a few short trips in the last week so no need to fill up.
  9. WI-790R

    WI-790R Been here awhile

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    @TrailTrauma You threw out the idea of using a different connector pair in the harness, since we couldn’t find a male mating connector. That was sounding like the way to go. But I came across cycleteminal.com, a nice selection of stuff there, and emailed the owner Joseph, asking if a male connector existed. He proposed kind of a hybrid version of what you proposed that eliminates cutting wires:

    Joseph confirmed that Sumitomo didn’t make a male, but that the terminals used in our IAT’s female connector will fit other non-sealed Sumitomo connectors like the HD 090-2:
    http://www.cycleterminal.com/hd-series.html

    This offers a solution without having to cut any wiring. But would require taking the socket terminals/wires out of the IAT connector housing, and inserting them into the HD 090-2. I happened to find a YouTube video showing how to take the IAT connector apart:


    I ordered a few HD 090-2 male and female connectors and will try this on my bike.
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  10. TrailTrauma

    TrailTrauma Nemophilist Supporter

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    That's great luck, and lateral thinking. Well done!
  11. braaap!

    braaap! Long timer Supporter

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    I'm following this dongle development with great interest as my bike has taken 3 prods of the starter of late. Cool or warmish ambient temps and it requires a few hits of the button to achieve an even idle. :dirtdog

    Until today... Mild, low 20C.

    :hmmmmm

    Key inserted and set to start, waited approx' 30 seconds for the fuel pump prime (putting on gloves)...
    Then, instead of just 'prodding' the start button, I actually gave it a firm press and held it down as the motor turned over... Engine fired straight up and held its idle... Let go of the starter button and all good!
    One hit start!

    Anyone care to do the same and report in with findings? Could it be that simple? Hold the start button on, rather than stab it?
  12. TrailTrauma

    TrailTrauma Nemophilist Supporter

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    I recall back in the day (2019?) the fad was to jab the button like a ninja. Oh how the times change...:gerg



    braaap, I can't recall, do you have the BP?
  13. t3scn

    t3scn Adventurer

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    That is correct, extra functions lists that Rally and Quickshifter additions. No obvious purpose other than a reminder of what is enabled or installed
  14. braaap!

    braaap! Long timer Supporter

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    I do have a BP but it’s never been unboxed as my bike always started first jab...
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  15. 1coolbanana

    1coolbanana Long timer

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    Time to unpack perhaps :-)
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  16. Gaulin

    Gaulin Orange (& Blue) Crush

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    It was a thing discussed by us OGs back in 2019, yup. Add it to the list of voodoo magic that's been tried to cure the 3 start. I changed my start method from holding the starter down, to a single momentary press, and back again a few times. The condition would sometimes change, but always return.

    The only thing that's worked for me is a few very gentle throttle inputs once fired. Still not 100% though.
  17. TrailTrauma

    TrailTrauma Nemophilist Supporter

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    This is all great feedback for anyone listening who can. It's like gathering information on a patient .. are we dealing with a triple vessel MI, or prinzmetal angina? Birth imminent or a Braxton Hicks fakeout? :D

    The more data the better. And from what you've also added, it looks like these bikes ebb in and out of the multi-push start problem. Now we just have to filter out all the other myriad of variables that might be associated. Weather (temp, humidity), Where the bike was stored, what quality fuel was used, mods and so on.

    In the end, though, it may all me moot if the circuit developed so generously by @WI-790R passes field testing. I still can't believe how fast that development happened, and production boards were produced. That's about as astounding to a guy like me as it was last year to see guys here 3D printing their own modified intake prefilter holders, or GPS mounts and so on.

    What a great time to be alive. :clap
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  18. SuperJimbo

    SuperJimbo n00b

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    <I bought my bike from a dealer 5700 feet above sea level and rode at that altitude for a few days before going home with no problems, I live at sea level and after having the bike at home for about two months the starting problem reared its ugly head. The coldest it gets where I live is about 10 degrees Celsius so not cold at all and my bike lives in a garage. I fitted a booster plug and that worked for a while until it didn't, I removed the booster plug and the problem was still there.>

    That would also seem to be barking up the right tree. To use deductive reasoning, look at the OEM and what their ambient conditions are At where the thing is built. What is the altitude at Mattighofen, etc?
    I've had the exact same thing happen with my 790R after adding the BP, but in NE TX we do have 92 octane readily available.
  19. SuperJimbo

    SuperJimbo n00b

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    SPARE PARTS MANUAL, ENGLISH ART.NO.: 3208201

    I downloaded that as a Pdf, and it seems to have a fairly comprehensive list of the connectors used. Regret the lack of a direct link to that but hope it helps.
  20. windblown101

    windblown101 Long timer Supporter

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    This may not help but I'll post it as a data point for the injector duty cycle at start up. I altered my Rapidbike map to not add any fuel at idle a few days ago and it is still starting on the first try but it's also not the dog days of summer when the problem has historically shown up. Just shot video on phone and did some screen grabs.

    Full cold start up.
    45 degrees.
    19% humidity
    Altitude 800ft.


    Grab one - Right at first kick over..
    KTM 01 - kick over.jpg


    Grab 2 at 2 second mark
    KTM 02 - 2 seconds.jpg

    Grab 3 - 30 second mark
    KTM 03 - 30 seconds.jpg

    Grab - 2 minute mark
    KTM 04 - 2 minutes.jpg

    Grab at the 5 minute mark. Injectors settling in to their full warm idle duty cycle.
    KTM 05 - 5 minutes.jpg
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